Method of making an earth-boring particle-matrix rotary drill bit

Abstract

A method of making an earth-boring rotary drill bit including a bit body configured to carry one or more cutters for engaging a subterranean earth formation. The method includes providing a plurality of hard particles in a mold to define a particle precursor of the bit body. The method also includes infiltrating the particle precursor of the bit body with a molten matrix material comprising a shape memory alloy forming a hard particle-molten matrix material mixture, wherein the hard particles are randomly dispersed within the molten matrix material. The method further includes cooling the molten matrix material to solidify a matrix material and form the bit body comprising a particle-matrix composite material having the plurality of hard particles randomly dispersed throughout the matrix material.

We claim: 
     
       1. A method of making an earth-boring rotary drill bit comprising a bit body configured to carry one or more cutters for engaging a subterranean earth formation, comprising: providing a plurality of hard particles in a mold to define a particle precursor of the bit body; infiltrating the particle precursor of the bit body with a molten matrix material comprising a shape memory alloy forming a hard particle-molten matrix material mixture, wherein the hard particles are randomly dispersed within the molten matrix material; and cooling the molten hard particle-molten matrix material mixture to solidify the mixture and form the bit body comprising a particle-matrix composite material. 
     
     
       2. The method of  claim 1 , further comprising configuring the particle-matrix composite material to undergo a reversible phase transformation between an austenitic phase and a martensitic phase. 
     
     
       3. The method of  claim 1 , wherein the molten matrix material comprises a molten Ni-based alloy, Cu-based alloy, Ti-based alloy, Co-based alloy or Fe-based alloy. 
     
     
       4. The method of  claim 3 , wherein the Cu-based alloy is a Cu—Zn—X alloy or a Cu—Al—Ni alloy, where X is Al, Si or Sn, or a combination thereof. 
     
     
       5. The method of  claim 3 , wherein the Ni-based alloy is an Ni—Ti alloy. 
     
     
       6. The method of  claim 3 , wherein the Fe-based alloy is an Fe—Mn—Si alloy. 
     
     
       7. The method of  claim 3 , wherein the Co-based alloy is a Co—Ni—Al alloy or a Co—Ni—Ga alloy. 
     
     
       8. The method of  claim 1 , wherein the hard particles comprise diamond, or metal or semi-metal carbides, nitrides, oxides, or borides. 
     
     
       9. The method of  claim 1 , further comprising inserting a blank into the mold such that upon cooling a bit body portion of the blank is metallurgically bonded to the matrix material. 
     
     
       10. The method of  claim 9 , further comprising attaching a shank portion of the metal blank to a shank. 
     
     
       11. The method of  claim 1 , further comprising inserting a shank into the mold such that upon cooling a bit body portion of the shank is metallurgically bonded to the matrix material.